A. FIELD OF THE INVENTION
This invention relates to anti-pollution apparatus and, in particular to improved thermal regeneration incineration systems.
B. PRIOR ART
Thermal regeneration equipment is known which comprises a plurality of heat-exchange beds or chambers in communication with a high temperature after-burner zone such as is shown in U.S. Pat. No. 3,895,918 to James Mueller. The exhaust gas from a factory, for example, is purified by passing through a first inlet bed into a high-temperature incinerator or after-burner zone where noxious or other undesired components are burned off or converted to less harmful substances. The heat-consumed gases are drawn from the high temperature zone through a second heat-exchange bed whose elements are thereby heated considerably.
Some of the exhaust fumes and gases fed to such thermal regeneration apparatus from the industrial process include chemicals such as solvents which, when ignited in the high temperature combustion zone, raise its temperature to excessive levels. Such elevated temperatures can be harmful to the valves, fans and other heat-sensitive equipment in the installation.
In certain known incinerators having heat-exchangers, the temperature of the combustion zone has been monitored so that when it starts to approach dangerously high temperature levels, the exhaust fumes to be purified are made to by-pass the inlet heat-exchange chamber and go directly to the combustion zone. Since the temperature of the industrial effluent may be at approximately ambient temperature, for example, it arrives at the combustion chamber in a relatively cool state. Furthermore, known incinerators are often designed so that the retention or dwell time of the effluent in that zone may be quite short, i.e., on the order of 0.5 seconds. These two factors, the low temperature of the input gas and the short dwell time, co-act so that the noxious fumes are not adequately combusted and, therefore, the exhaust gases are not purified to the desired extent.
If, in such a case it is desired to compensate for those low-temperature input gases directly into the combustion zone where they will dwell for a short time, by raising the temperature in the zone by a considerable amount, this would result in a dangerous operating condition.
It is therefore among the objects of the present invention to provide an improved system for preventing the generation of excessivey high temperatures in the combustion zone so as to avoid harmful effects on the associated equipment and personnel.
It is also among the objects of the invention to provide for continuous operation of a thermal regeneration system with satisfactory purification efficiency.
Another object is to permit the apparatus to be smaller than would otherwise be the case.